Breath alcohol analyzers, otherwise known as breathalyzers, estimate blood alcohol content (BAC) to determine levels of alcohol intoxication. Breathalyzers are used by law enforcement officials, but breath testers can also be purchased for personal use, either for one to test themselves before driving, or for parents to test their children. To learn how breathalyzers work, read The Guide to Breathalyzer Tests and our interviews with breathalyzer experts Nima Parto, Ed Gollar and Barry Knott.